Hydraulic snubber



Nov; 28, 1944. M, D ISELY 2,363,867

HYDRKULI C SNUBBER Filed Feb. 8, 1944 INVENTOR. /V. J. A354) Patented Nov. 28, 1-944 13 Claims.

The invention here disclosed relates to snubbers and particularly such as for controlling and limiting the 'roll of a railway car body or the like.

The periodic roll of a railway car body may be reduced by restricting the rate of contraction and expansion of the springs supporting the car body to a point below their normal harmonic frequency.

The springs supporting such a body should be permitted to flex freely when the wheels encounter an irregularity of such extent as to pro,-

duce .a noticeable jolt in the car or a pounding effect upon the track, if the spring action were restricted.

Further, the. spring action should be positively and severely limited before the springs are driven solid.

Objects of the present invention are to attain the conditions outlined above and to accomplish such improvements in snubbing and spring operation within the limits of simple, practical and efficient structure.

The foregoing and other desirable objects are attained by the novel features of construction,

combinations and relations of parts hereinafter described, illustrated by way of example in the accompanying drawing and broadly covered in the claims.

The drawing accompanying and forming part of the specification illustrates certain structural embodiments of the invention, but it is to be understood that structure may be modified and changed all within the true intent and broad scope of the invention as hereinafter defined and claimed.

Fig. 1 is a broken longitudinal sectional and more or less diagrammatic view illustrating one simple embodiment of the invention.

Fig. 2 is a cross-sectional view as on substantially the plane of line 2-2 of Fig. 1.

Fig. 3 is a broken sectional detail of a modified form of impact release valve.

In the example shown, a piston 5 operates within a cylinder 6, under control of tapered metering pins 1, 8, extending inwardly from opposite ends of the cylinder through an orifice 9, in the piston. These metering pins may' be separately formed or be simply opposite end portions of a compound double acting metering pin structure held between the opposite end heads of the cylinder. The piston and cylinder are suitably formed for connection with the relatively movable parts which are to be linked together, such as the sprung and unsprung members of the truck; i

The double acting metering action 'thus effected reduces the rate of contraction and expansion of the springs supporting the car body below the normal harmonic. frequency, eliminating side roll or other objectionable movements caused by spring harmonics.

Special impact release valves, in conjunction with the metering action, exert control to enable the springs to flex freely to avoid pounding action. These automatic impact release devices are shown in the form of oppositely facing disc valves H], II, over ports l2, l3, in a partition M,

defining chambers l5, l6, incommunicationwith opposite ends of the cylinder by ports l1, l8.

Springs l9. 2}, hold the valve discs seated under normal or balanced conditions and the tension of these springs isregulated by pistons 2|,22, operating in piston chambers 23, 24, connected with the chambers l6, l5, at the opposite sides of the partition ll, by the restricted ports or passages 25, 26.

In operation, increasing pressure in .the lower chamber l6, occasioned by downward movement of piston 5, in cylinder 6, tends tolift valve l0, off its seat. The piston chamber 23. being connected with chamber I6, through restricted pas sage 25, is subjected to this same increase in pressure enabling piston 2|, operating in chamber 23, to increase the tension of the spring l9, holding valve III, to its seat.

The upper surface of piston 2|, which is the surface exposed to pressure from chamber IS, in the illustration, is greater than the undersurface of valve l0, exposed to that same pressure and consequently this valve will remain closed, if the pressure increase is gradual.

. If however, the pressure in cylinder I6, is suddenly increased, as by a jolt or bump, the limited .-or restricted flow possible through passage 25,

will delay the action of such increased pressure on piston 2 I, to the extent that the pressure tending to lift valve III, will momentarily exceed the closing pressure applied from the opposite side, enabling valve Ill, to open and release excess pressure into the upper chamber l5.

When pressure in chamber l5 exceeds that in chamber IS, the piston 2i, providing the abutment for spring [9, will move up, expelling fluid rrom chamber 23, back through passage 25, into the lower chamber l6, until the expanding tension of spring [9, equals the pressure on the un'- dersurface of piston 2|, minus pressure upon the upper surface of the same.

The pressures mentioned are total for the particular surfaces, rather than-pressures per square inch.

As the snubber piston 5 moves in either direction described of the impact release valves It and I Travel of piston :5, toward opposite ends of the cylinder is progressively slowed down by reason of the double acting taper pin construction 1, 8, reducing the efiective size of the metering orifice and because of the further fact of the piston cutting off the ports ll, it, to the impact release valves as it approaches the limits of its travel. After cutting ofi one or the other of ports ll, l8, controlling the valved bypass around the piston, any further movement will then be governed entirely by permitted flow through the greatly reduced piston orifice and the relative movement of parts thus more or less abruptly checked beforethe supporting springs are compressed to solid condition.

In the form of the invention considered, the areas of thevalve disc and of the spring abutment exposed to the chamber where they are located, in the case of chamber it, the upper surface of valve it and the lower surface of abutment piston 2!, are substantially equaL'so that operation of the impact release valve is depend ent entirely upon the rate of pressure increase in the opposite chamber, in this instance the chamber l6.

In the modified form of the invention shown in Fig. 3, the valve 'disc' is made larger, so that the upper surface of the same, exposedto pressure in chamber 55, is greater than the upper and lower surfaces of spring abutment 2i, and lower exposed surface of valve it, the last mentioned three surfaces being indicated as substantially equal.

In this form of the invention, it will be seen that pressure in the chamber in which the valve is located, in this case, chamber l5, becomes a factor in the valve opening operation. This Extended or extreme spring action. is kept under control by using the piston to reduce and cut ofi the bypass and thereby to place final control in the fully restricted metering orifice.

In view of its many applications and the broad scope of the invention, the terms employed herein have been used primarily in a descriptive rather than in a limiting sense and are to be so construed, except possibly for such limitations as may be imposed by state of the prior art What is claimed is: 1. A snubber of the character disclosed, comprising companion piston and cylinder elements,

-a double acting metering couple associated with said piston and cylinder elements for progressivepressure sources tending to open the valves.

2. A snubber of the character disclosed, comprising companion piston and cylinder elements, a double acting metering couple associated with said piston and cylinder elements for progressively slowing relative movement of the piston element in the cylinder element in opposite directions, a bypass around opposite sides of the piston element, impact release valve mechanism in said bypass for automatically releasing sudden pressure increase through said bypass in opposite directions and including oppositely acting pressure opening valves and pressure actuated valve closing means having restricted connection with the pressure sources tending to open said valves.

3. A nubber of the character disclosed, comprising companion piston and cylinder elements, a double acting metering couple associated with said piston and cylinder elements for progressively slowing relative movement of the piston element in the cylinder element in opposite directions, a bypass around opposite sides'of the piston element, impact release valve mechanism in said bypass for automatically releasing sudden pressure increase through said bypass in opposite directions, said bypass being in communication at opposite ends with opposite ends of thecylinelement, oppositely acting pressure opening valves in said bypass, pressure actuated pistons for applying closing force to said valves and restricted pressure supply connections extending to said valve closing pistons from the pressure sides for opening the respective valves.

ly slowing relative movement of the piston element in the cylinder element in opposite directions, a bypass around opposite sides of the piston element and impact release valve mechanism in said bypass-for automatically releasing sudden ll.

5. A snubber of the character disclosed, comprising companion piston and cylinder elements, a bypass connecting opposite ends of the cylinder element, oppositely acting pressure opening valves in said bypass, pressure actuated pistons for applying closing force to said valves, restricted pressure supply connections extending to said valve closing pistons from the pressure sides for opening the respective valves and said bypass having ports opening into opposite end portions of the cylinder element and controllable by the pist element in its movement in said end portions of the cylinder element.

6. A roll limiting snubber, comprising companion piston and cylinder elements, a metering couple for controlling normal slower movements of piston and cylinder element and impact release valves. for relieving sudden pressure increases occasioned by more abrupt relative movements of said piston and cylinder elements and including oppositely acting pressure opening valves, closing springs acting on said valves and pressure operated abut-ments for said springs having restricted connection with the pressure sources tending .to open the respective valves with which said spring abutments are associated.

7. A roll limiting snubber, comprising companion piston and cylinder elements, a metering couple for controlling normal slower movements valves for relieving sudden pressure increases occasioned by more abrupt relative movements of said piston and cylinder elements and means for automatically cutting of! said impact release valves from the cylinder element in extreme movements of the piston element therein.

8. A snubber of the character disclosed, com-- prising a cylinder and a piston operating therein, a bypass connecting opposite ends of the cylinder, said bypass having a partition wtih valve passages therethrough, valves controlling said passages and disposed at opposite sides of said partition, closing springs acting on said valves, piston abutments for said springs and restricted pressure supply connections extending to said spring abutment piston from the opposite sides of said partition.

9. A snubber of the character disclosed, comprising a cylinder and a piston operating therein, a bypass connecting opposite ends of the cyl-- inder, said bypass having a partition with valve passages therethrough, valves controlling said passages and disposed at opposite sides of said partition, closing springs acting on said valves, piston abutments for said springs, restricted pressure supply connections extending to said spring abutment pistons from the opposite sides of said partition, a double tapered metering pin extended inwardly from the opposite ends of the cylinder and the piston having a metering orifice through which said metering pin extends.

10. A snubberof the character disclosed, comprising a cylinder and a piston operating there- 'in, a bypass connecting opposite ends of the cylinder, said bypass having a partition with valve passages therethrough, valves controlling said passages and disposed at opposite sides of said partition, closing springs acting on said valves,

piston abutments for said springs, restricted pressure supply connections extending to said spring abutment pistons from the opposite sides of said partition, said bypass having ports opening into opposite end portions of the cylinder and coni trollable by the piston operating therein, said piston having a metering orifice and a double acting metering pin extended inwardly from opposite ends of the cylinder through said metering 11. A snubber of the character disclosed, comprising companion piston and cylinder elements, a bypass around the piston element and an impact release valve controlling said bypass and including slow acting pressure operated means for applying pressure from the pressure end of said bypass for holding said impact release valve closed; said impact release valve being pressure operated in the opening direction and subjected to the full pressure developed by said piston and cylinder elements to be thereby quickly and fully operable to release sudden impact pressure, and said slow acting pressure operated means includ-' ing a valve closing spring, a movable pressure operable spring abutment and a restricted pressure connection from the pressure end of the bypass to said movable spring abutment.

' 12. A snubber of the character disclosed, com- ":prising companion piston and cylinder elements,

a bypass around the piston element and an impact release valve controlling said bypass and including slow acting pressure operated means for applying pressure from the pressure end of said bypass for holding said impact release valve closed, said bypass having a port opening to the cylinder element and controlled by the piston element and a metering couple controlling movement of the piston element in the cylinder element independently of control exercised by said impact release valve and independently of the cutofi control eflected by the piston element.

13. A snubber of the character disclosed, comprising companion piston and cylinder elements, a bypass around the piston element and an impact release valve controlling said bypass and including pressure actuated means for holding said valve closed anda time delay fluid flow supply connection to said pressure actuated means from the higher'pressure end of said bypass, said impact release valve being pressure operable in the opening direction and exposed to the full pressure developed by the companion piston and cylinder elements and said pressure actuated means for holding the valve closed including a valve closing spring and a pressure operable abutment for said spring, said time delay fluid flow supply connection extending, from the higher pressure end or the bypass to that side of the movable spring abutmentfor displacing it in the valve closing direction, the opposite side of said spring abutment being subjected to pressure from the lower pressure end of the bypass and said impact release valve being subjected to said'pressure' in the valve closing direction, said impact release relation. MALCOLM D. ISELY. 

